Pentachlorophenol
PCP·Affects liver, kidneys, reproductive
A chlorinated wood preservative phased out for residential use in 1987 but still contaminating soil and groundwater at industrial sites. EPA-classified as a likely human carcinogen.
PCP
EPA limit
0.001 mg/L (MCL)
Most at risk
Well-water households near former wood-treatment plants, sawmills, or utility-pole storage yards
Found in
City water · Well water
AquaOx filters
YesActivated coconut shell carbon
What it does to you
Health effects
Pentachlorophenol is classified by the EPA as likely to be carcinogenic to humans, with evidence pointing to elevated rates of liver cancer and non-Hodgkin lymphoma in chronically exposed workers. The IARC reclassified it as a Group 1 human carcinogen in 2019.
The liver and kidneys are the primary target organs. PCP also acts as an endocrine disruptor and is associated with reproductive and developmental effects in animal studies. Acute high-dose exposure can cause fever, sweating, and metabolic disruption because PCP interferes with cellular energy production.
Commercial PCP was historically contaminated with dioxins and furans during manufacture, which compound the health concern at contaminated sites.
Where it comes from
How it gets into your water
PCP was used heavily from the 1930s through the 1980s to treat utility poles, railroad ties, fence posts, and lumber against rot and insects. The compound binds to soil but slowly leaches into groundwater over decades, especially at former treatment plants, sawmills, and pole storage yards.
Residential use was banned in 1987, and industrial wood-treatment use was phased out in 2021 under EPA action. Legacy contamination persists at thousands of sites across the US, particularly in the South and Pacific Northwest where wood-treatment operations were concentrated.
Former wood-treatment plants
Soil and groundwater contamination at industrial sites
Utility-pole storage yards
Drip and leaching from treated poles
Legacy groundwater contamination
Persists for decades after use stopped
Surface water near industrial sites
Stormwater runoff from contaminated soil
Find out for yourself
Is it in your water?
Public utilities test for PCP under the EPA's primary drinking water regulations and report results in the annual Consumer Confidence Report. Detections in well-run city systems are uncommon.
Well-water households should test for PCP if their property is downgradient of a former wood-treatment facility, sawmill, or utility-line easement where poles were stored. State environmental agencies maintain databases of contaminated sites that can help you assess proximity risk.
The fix
How AquaOx filters it
Pentachlorophenol is filtered efficiently by activated carbon. The coconut shell carbon stage in The AquaOx adsorbs chlorinated phenols as water passes through the bed, with independent testing showing reductions well above 90%.
For households on wells near known contamination, we recommend The AquaOx as the primary defense plus the under-sink RO for additional drinking-water polish. If iron or hydrogen sulfide is also present, our FE or RE Edition adds those stages.